Parse multiple group name. Not yet finished fully though.

tiny_obj_loader.h

@@ -1,5 +1,5 @@
 //
-// Copyright 2012, Syoyo Fujita.
+// Copyright 2012-2013, Syoyo Fujita.
 //
 // Licensed under 2-clause BSD liecense.
 //
@@ -49,9 +49,11 @@ typedef struct
 /// 'shapes' will be filled with parsed shape data
 /// The function returns error string.
 /// Returns empty string when loading .obj success.
+/// 'mtl_basepath' is optional, and used for base path for .mtl file.
 std::string LoadObj(
     std::vector<shape_t>& shapes,   // [output]
-    const char* filename);
+    const char* filename,
+    const char* mtl_basepath = NULL);
 
 };